Purpose Retinal oximetry measures oxygen saturation in retinal vessels. With the introduction of a mobile handheld prototype oximeter, this technique will become available for a broader patient... Show morePurpose Retinal oximetry measures oxygen saturation in retinal vessels. With the introduction of a mobile handheld prototype oximeter, this technique will become available for a broader patient population including bedridden patients and newborn babies. The objective is to determine the sensitivity of this handheld oximeter in room air and during isocapnic hyperoxia. A comparison is made between the handheld oximeter and the Oxymap T1.Methods Thirteen young healthy subjects with a mean age of 25 +/- 2 years were recruited at the Leiden University Medical Center. Retinal oximetry images were acquired during normoxia and during isocapnic hyperoxia for both the prototype oximeter and the OxymapT1. Isocapnic hyperoxia was induced with the dynamic end-tidal forcing technique. For both oximeters, the oxygen saturation and vessel width were measured with Oxymap Analyzer software. The hyperoxic state was verified with blood gas analysis.Results The mean oxygen saturation measured with the handheld oximeter in arterioles was 91.3% +/- 3.9% during normoxia and 94.6% +/- 3.9% during hyperoxia (p = 0.001). Oxygen saturation in venules was 56.3% +/- 9.8% during normoxia and 82.2 +/- 7.4% during hyperoxia (p < 0.001). For the Oxymap T1, the mean oxygen saturation for arterioles was 94.0% +/- 2.6% during normoxia and 95.4%+/- 3.2% during hyperoxia (p = 0.004). For the venules, the oxygen saturation was during normoxia 58.9%+/- 3.2% and 84.3 +/- 4.0% during hyperoxia (p 0.001).Conclusion The handheld retinal oximeter is sensitive to the changes in inhaled oxygen concentration. A small increase in oxygen saturation was measured in the arterioles and a larger increase in the venules. The handheld oximeter gives similar values as the 'gold standard' Oxymap T1 oximeter. Show less
Brouwer, N.J.; Marinkovic, M.; Bleeker, J.C.; Filali, M. el; Stefansson, E.; Luyten, G.P.M.; Jager, M.J. 2020
Purpose: To compare retinal vessel oxygenation in eyes with an untreated choroidal nevus or choroidal melanoma. Methods: The affected and fellow eye of patients with an untreated choroidal nevus (n... Show morePurpose: To compare retinal vessel oxygenation in eyes with an untreated choroidal nevus or choroidal melanoma. Methods: The affected and fellow eye of patients with an untreated choroidal nevus (n = 42) or choroidal melanoma (n = 45) were investigated using noninvasive retinal oximetry (Oxymap T1). Oxygen saturation of arterioles (ArtSat) and venules (VenSat) was determined, together with the arteriovenous difference (AV-difference). Results: In choroidal nevus patients, retinal oximetry did not differ between the affected and fellow eye: the mean ArtSat was 94.5% and 94.2% (P = 0.56), the VenSat was 60.5% and 61.3% (P = 0.35), and the AV-difference was 34.0% and 32.9% (P = 0.18), respectively. In choroidal melanoma patients, alterations were detected: the mean ArtSat was 94.8% and 93.2% (P = 0.006), the VenSat was 58.0% and 60.0% (P = 0.014), and the AV-difference was 36.8% and 33.2% (P < 0.001), respectively. The largest increase in AV-difference was observed between the retinal halves without the lesion in melanoma eyes compared with the corresponding half in the fellow eye (37.5% vs. 32.1%, P < 0.001). Conclusion: Although retinal oximetry was not significantly altered in eyes with a choroidal nevus, eyes with choroidal melanoma showed an increased ArtSat and decreased VenSat, leading to an increased AV-difference. These changes may be caused by inflammation and a higher metabolism, with larger oxygen consumption, leading to altered blood flow and intraocular oxygen relocation. Show less
